Moderators Youthman Posted October 28, 2008 Moderators Share Posted October 28, 2008 I have an Onkyo M501 2 channel amp. I haven't had it hooked up for about a month since we moved and now when I hook it up, I get a pop sound through the speakers so I quickly shut it down. I switched the speaker wires from A to B channel and same thing happened. I unplugged the speaker wire and the RCA from the amp and just plugged it into the wall. The amp protection button is lit. Any ideas why this is happening and how to fix it? Has the amp just died? Quote Link to comment Share on other sites More sharing options...
wuzzzer Posted October 28, 2008 Share Posted October 28, 2008 Any stray strands of copper around the speaker outputs? Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 28, 2008 Author Moderators Share Posted October 28, 2008 No stray strands that I can see. I just hooked it up again to the wall, no RCA's or speaker wire plugged in. The Protection button turns on for a few seconds, then turns off. I believe this is normal. I am afraid to hook it back up to my speakers though. I really don't like hearing that pop sound at the beginning. Not sure why this is happening. Quote Link to comment Share on other sites More sharing options...
WMcD Posted October 29, 2008 Share Posted October 29, 2008 The obvious thought is that some changed in the interim. I think you're correct about the protection light coming on at start-up. Typically, devices will power on all indicators at start up as sort of a lamp test to show the indicator works. If you have some headphones, I'd use them to listen with the speakers disconnected as any external inputs. Try listening to FM. Of course in view of the pop, maybe use expendable ones and don't put them directly on your ears. The headphones are fed by the same output as the speaker output. At least that way, you'll be eliminating the speakers as the problem. Earphones draw little current and should not trip any protection circuit. Then . . . I don't know. I make wiring mistakes from time to time and therefore would check the wiring at the speaker end and the amp end. Twice. The pop could be what is called "dc offset" at the amp output; a bad thing. There should be no voltage at the output when there is no signal. That is the sign of an amp problem. If you take the grills off the speaker the woofer diaphragm will jump from the d.c. BTW, do both speakers pop? I know it can be so startling that it is difficult to tell. If only one does it mgiht narrow the search. Wm McD Quote Link to comment Share on other sites More sharing options...
Guest " " Posted October 29, 2008 Share Posted October 29, 2008 put it on a variac and bring the power up very slowly until the protection circut trips. repeat the processand stop at any point before the point it tripped. let it sit there for a while. see if you can pass the point it previously tripped at. If the tripping point changes you have a power supply capacitor problem. if the point of tripping doe not change, you have a semi conductor problem. in either case, you need to get the amp serviced....could be quite expensive. Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 29, 2008 Author Moderators Share Posted October 29, 2008 I'll try the headphone suggestion tonight. Yesterday, I turned on the amp before I turned on the amp without the receiver being turned on and the pop occurred. I thought, maybe I need to have the receiver on first so I did that, then turned on the amp, same thing. I wasn't about to do it again in fear of blowing my 83's up. The amp does not have gain levels, only on or off and A or B. If it is broke, it's going in the trash, no sense servicing a 10 year old amp. I'll just get another amp. I just wanted to see if there was something I was missing or doing wrong. I had it hooked up for awhile and never had any problems with it. Strange that we move and it starts acting up. I'll let you know what I find out with the headphones. Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 29, 2008 Share Posted October 29, 2008 Does it thump with no input cable connected? If it does, then try it again with the input shorted. Also, did you ever hear relays clicking and do they click now? I don't thnk bad power supply caps are going to be a source of popping...the popping occurs because caps are charging too fast (bad caps usually charge slower or don't charge at all). Btw, what is the power handling of the amp? Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 29, 2008 Author Moderators Share Posted October 29, 2008 Don't remember hearing a thump. I do hear a click when the amp turns on. The amp is a 150 watt x 2. Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 29, 2008 Share Posted October 29, 2008 So no thump, just a loud high/mid frequency pop? Kinda like a cork being removed, but really loud? Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 29, 2008 Author Moderators Share Posted October 29, 2008 Sorry my description isn't probably the most accurate. I just know that it didn't sound good and I'm hesitant to try it again with my RF-83's. It wasn't really loud but loud enough. Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 29, 2008 Author Moderators Share Posted October 29, 2008 Ok, I hooked up the headphones to the front jack. I connected the amp to the receiver via the pre-outs. Once the amp powers up, a loud buzz comes through the headphones. I then unplugged the RCA's from the receiver but left the RCA plugged into the amp, still a buzz. Removing the RCA from the amp removes the buzz, all is silent. Any thoughts as to what is going on here? Quote Link to comment Share on other sites More sharing options...
DU73 Posted October 29, 2008 Share Posted October 29, 2008 Don’t you have a 12volt trigger going from your Onkyo or Yamaha to your power amp? My power amp power cord is connected to the back of my Yamaha, then I use a ‘12 volt trigger’ (12volt cable) from your receiver to your power amp. I leave the power amp on and off button on all the time 24 hours a day, but I have the power cord of the power amp connected to the Yamaha, so all I have to do is turn on my receiver and then instantly both the receiver(pre) and power amp turn on at the same time. The 12v trigger ensures there is no damage to either equipment or speakers, well that is how I understand it. You would need a 12 volt output from receiver and a 12 volt input on power amp. Maybe try this. Good luck. Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 29, 2008 Author Moderators Share Posted October 29, 2008 Yes, I have two "AC Outlets" on the back of the Yamaha. I would think it would be better for the amp to have it's own power supply than for both the receiver and the amp to use the same one. I have not tested it but in theory, how would that prevent the amp from sending a popping sound through to the speakers? Yes, I could leave the power button on the amp turned on all the time but internal components of the amp still have to power up. I would think this is where the pop sound is coming from. Michael Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 29, 2008 Author Moderators Share Posted October 29, 2008 I hooked the amp up to the Onkyo with no speakers plugged in, same results, even when plugging the amp into the rear of the receiver. At this point, I need to find a set of junk speakers laying around somewhere so I can test the amp out again without fear of blowing them. Quote Link to comment Share on other sites More sharing options...
DU73 Posted October 30, 2008 Share Posted October 30, 2008 Yes, I have two "AC Outlets" on the back of the Yamaha. I would think it would be better for the amp to have it's own power supply than for both the receiver and the amp to use the same one. I have not tested it but in theory, how would that prevent the amp from sending a popping sound through to the speakers? Yes, I could leave the power button on the amp turned on all the time but internal components of the amp still have to power up. I would think this is where the pop sound is coming from. Michael As for the power amp being powered by a separate ac outlet, I also think that will be the absolute best option. But I also figured that is probably why Yamaha put the an AC at the back of their receiver for this reason. I have also once connected my power amp to a separate outlet and found no noticeable difference. I suppose I have it set up this way for convenience more than anything else. As for the 12 volt trigger fixing the problem – to be honest I have no idea if that will fix the problem, just thought it would not hurt trying, that is all. I wish you all the luck in getting this fixed as I know it must be very frustrating. Good luck Michael. EDIT: "As for the power amp being powered by a separate ac outlet, I also think that will be the absolute best option. But I also figured that is probably why Yamaha put the an AC at the back of their receiver for this reason." - i have made a few calls and spoke to people and read manuals it appears this is not what the Yamaha's ac outlet is designed for. thanks Youthman - apparantly I could have blown the internal parts os the Yamaha. Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 30, 2008 Author Moderators Share Posted October 30, 2008 To be honest, I'm not really frustrated. It has served it's purpose. I would rather have a 200 watt x 5 amp. I don't think I would notice any difference between it and the Yamaha. I was going to sell it and a forum member was very interested in it but I wanted to test it before him paying for it since I hadn't had it hooked up in a month. Good thing I checked. So I let him know the amp was having issues but would let him know if I got them resolved. No biggie if it dies. Just would have been nice to sell it. Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 30, 2008 Author Moderators Share Posted October 30, 2008 As for the power amp being powered by a separate ac outlet, I also think that will be the absolute best option. But I also figured that is probably why Yamaha put the an AC at the back of their receiver for this reason. I would see no problem having a DVD player or another input device hooked up to these outlets but I just can't see having a 1000 watt amp hooked up to the Yammie could be good since it needs a lot of current from the wall. Note: I am not an engineer and I know very little about electricity except that it hurts when you touch it. [] I'm just speaking from my logical brain. Someone else correct me if I'm wrong in this. Quote Link to comment Share on other sites More sharing options...
DU73 Posted October 30, 2008 Share Posted October 30, 2008 As for the power amp being powered by a separate ac outlet, I also think that will be the absolute best option. But I also figured that is probably why Yamaha put the an AC at the back of their receiver for this reason. I would see no problem having a DVD player or another input device hooked up to these outlets but I just can't see having a 1000 watt amp hooked up to the Yammie could be good since it needs a lot of current from the wall. Note: I am not an engineer and I know very little about electricity except that it hurts when you touch it. I'm just speaking from my logical brain. Someone else correct me if I'm wrong in this. You may be right here Youthman, I have been running it like this for months now without any problems, but clearly I don’t want it to cause any problems going forward. The problem is the Rotel I’m using does not have a remote, so I can turn on the Yamaha with the remote but not the Rotel, so I have connected it this way for convenience only. I will stop using it this way until I find out if safe. I’ll ask locally. Does anyone else connect their power amp power cord to the back of the receiver (pre) ac outlet and if so have they experienced any problems. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted October 30, 2008 Share Posted October 30, 2008 put it on a variac and bring the power up very slowly until the protection circut trips. repeat the processand stop at any point before the point it tripped. let it sit there for a while. see if you can pass the point it previously tripped at. If the tripping point changes you have a power supply capacitor problem. if the point of tripping doe not change, you have a semi conductor problem. in either case, you need to get the amp serviced....could be quite expensive. Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted October 30, 2008 Author Moderators Share Posted October 30, 2008 I thought the protection was tripping, but now I don't think it is. When I powered on the amp, the speakers popped and I immediately turned off the amp, before giving it any time to turn off. As I mentioned, with nothing plugged into the amp, when I turn it on, the protection light comes on, then after a few seconds, it turns off. This is just the boot process. So probably the same happens when my speakers are hooked up, the popping sound causes me to immediately turn off the amp in fear of damaging my speakers. As I mentioned, at this point, I need some cheap speakers that I don't mind blowing up to test the amp to see what is going on. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.